<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js框选 变色</title>
    <style>
        body {
            padding: 0;
            margin: 0;
            overflow-y: hidden;
        }

        .table {
            width: 990px;
            height: 850px;
        }

        .table tr {
            height: 50px;
            overflow: scroll
        }

        .table-container {
            position: absolute;
            top: 0;
            left: 200px;
            height: 750px;
            width: 990px;
            overflow-y: scroll;
            overflow-x: hidden;
        }

        #title {
            background-color: #BDE4F4;
        }

        .fileDiv {
            background-color: #FEFF89;
        }

        .seled {
            border: 1px solid red;
            background-color: #D6DFF7;
        }
    </style>
</head>

<body>
    <div class="table-container" id="tablewrapper">
        <table class="table" id="dataGrid" align="center">
            <tr id="title">
                <th>&nbsp;</th>
                <th>水果</th>
                <th>蔬菜</th>
            </tr>
            <tr id="tb1" class="fileDiv">
                <td><input type="checkbox" name="idarray" value="1" /></td>
                <td>苹果</td>
                <td>菠菜</td>
            </tr>
            <tr id="tb2" class="fileDiv">
                <td><input type="checkbox" name="idarray" value="2" /></td>
                <td>梨</td>
                <td>白菜</td>
            </tr>
            <tr id="tb3" class="fileDiv">
                <td><input type="checkbox" name="idarray" value="3" /></td>
                <td>葡萄</td>
                <td>萝卜</td>
            </tr>
            <tr id="tb4" class="fileDiv">
                <td><input type="checkbox" name="idarray" value="4" /></td>
                <td>桃子</td>
                <td>土豆</td>
            </tr>
            <tr id="tb5" class="fileDiv">
                <td><input type="checkbox" name="idarray" value="5" /></td>
                <td>苹果</td>
                <td>菠菜</td>
            </tr>
            以下省略十行……
        </table>
        <!-- <div id="tablewrapper"></div> -->
    </div>

</body>
<script type="text/javascript">
    var allpro2 = [];
    var index = 0;

    window.onload = function () {
        document.onmousedown = function () {
            var evt = window.event || arguments[0];

            var startX = (evt.x || evt.clientX);
            var startY = (evt.y || evt.clientY);

            if (startX > 220 && startX < 1210) {
                var selList = [];
                var fileNodes = document.getElementsByTagName("tr");
                for (var i = 0; i < fileNodes.length; i++) {
                    if (fileNodes[i].className.indexOf("fileDiv") != -1) {
                        fileNodes[i].className = "fileDiv";
                        selList.push(fileNodes[i]);
                    }
                }
                allpro2 = [];       //选错区域后重选则清空数组
                var yheight = document.getElementById("tablewrapper");
                if (yheight.scrollTop > 0) {      //判断初始滚动条是否为0 为后面是否加滚动条高度设置判断值
                    var istrue = true;
                }
                paint(yheight, selList, startX, startY, istrue);

            }
        }
    };


    function paint(yheight, selList, startX, startY, istrue) {
        var isSelect = true;
        var selDiv = document.createElement("div");
        selDiv.style.cssText = "position:absolute;width:0px;height:0px;font-size:0px;margin:0px;padding:0px;border:1px dashed #0099FF;background-color:#C3D5ED;z-index:1000;filter:alpha(opacity:60);opacity:0.6;display:none;";
        selDiv.id = "selectDiv";
        document.body.appendChild(selDiv);

        selDiv.style.left = startX + "px";
        selDiv.style.top = startY + "px";

        var _x = null;
        var _y = null;


        document.onmousemove = function () {
            evt = window.event || arguments[0];
            if (isSelect) {
                if (selDiv.style.display == "none") {
                    selDiv.style.display = "";
                }

                _x = (evt.x || evt.clientX);
                _y = (evt.y || evt.clientY);

                selDiv.style.left = Math.min(_x, startX) + "px";
                selDiv.style.top = Math.min(_y, startY) + "px";
                selDiv.style.width = Math.abs(_x - startX) + "px";
                selDiv.style.height = Math.abs(_y - startY) + "px";
            }
        };


        document.onmouseup = function () {
            if (selDiv) {
                if (istrue) {
                    selDiv.style.height = Math.abs(_y - startY) + "px";
                    selDiv.style.top = Math.min(_y, startY) + yheight.scrollTop + "px";
                } else {
                    selDiv.style.height = Math.abs(_y - startY) + yheight.scrollTop + "px";
                }
                var _l = selDiv.offsetLeft, _t = selDiv.offsetTop;
                var _w = selDiv.offsetWidth, _h = selDiv.offsetHeight;
                for (var i = 0; i < selList.length; i++) {
                    var sl = selList[i].offsetWidth + selList[i].offsetParent.offsetParent.offsetLeft; //获取父元素table距离左边距离
                    var st = selList[i].offsetHeight + selList[i].offsetTop;

                    if (sl > _l && st > _t && selList[i].offsetLeft < _l + _w && selList[i].offsetTop < _t + _h) {
                        if (selList[i].className.indexOf("seled") == -1) {
                            selList[i].className = selList[i].className + " seled";
                        }
                    } else {
                        if (selList[i].className.indexOf("seled") != -1) {
                            selList[i].className = "fileDiv";
                        }
                    }
                }
            }

            isSelect = false;
            if (selDiv) {
                document.body.removeChild(selDiv);
                showSelDiv(selList);
            }
            revs1();
            selList = null, _x = null, _y = null, selDiv = null, startX = null, startY = null, evt = null;
        }
    }

    function showSelDiv(arr) {         //确定选中范围更新数组allpro2
        for (var i = 0; i < arr.length; i++) {
            if (arr[i].className.indexOf("seled") != -1) {
                var allpro1 = document.getElementById(arr[i].id).getElementsByTagName("td")[0].getElementsByTagName("input")[0];
                allpro2.push(allpro1);
            }
        }
    }


    function revs1() {        //反选函数
        if (allpro2.length > 0) {
            for (var i = 0; i < allpro2.length; i++) {
                if (allpro2[i].type == "checkbox" && allpro2[i].checked == true) {
                    allpro2[i].checked = false;
                } else if (allpro2[i].type == "checkbox" && allpro2[i].checked == false) {
                    allpro2[i].checked = true;
                }
            }
        }
        allpro2 = [];
    }
</script>

</html>